The present invention relates, in general, to a module of a modular drive system having at least two modules disposed in neighboring relationship and electrically connected to each other by a d.c. voltage intermediate circuit, and more particularly to a front cover for attachment to such a module.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Siemens-Catalog DA 65.11-2001, entitled “SIMOVERT MASTERDRIVES Motion Control”, chapter 6, in particular page 6/47, discloses a modular drive system which includes a capacitor module, a feed module with operator panel and seven inverter modules of different outputs. These modules are arranged side-by-side. The intermediate circuit busbar connection of these modules is implemented by a three-phase rail system which includes a plus conductor rail, minus conductor rail and PE (“Potencial Erde”=ground potential) conductor rail. The conductor rails are constructed as standard copper rails. These conductor rails are guided in insulated manner in a guide unit above the modules. The intermediate circuit voltages is generated in the feed module and supported by the capacitor module. The three-phase rail system distributes the generated intermediate circuit d.c. voltage to all inverter modules. In addition, the feed module produces a supply voltage of, for example, 24 V which is supplied to the inverter modules via a two-core cable. This supply voltage is required for feeding the electronic components of the inverter modules.
Siemens-Catalog DA 65.4-2001, entitled “SIMODRIVE 611 universal and POSMO”, chapter 6, in particular page 6/26, discloses a modular drive system having modules, with each module having in the lower front portion two stacked intermediate circuit conductor rails. Each intermediate circuit conductor rail includes a connection bracket articulated on one side and a contact screw. By means of these two connection brackets, the intermediate circuit conductor rails of an inverter module are electrically connected to corresponding intermediate circuit conductor rails of a neighboring inverter module. Each connection bracket hooks hereby behind a corresponding contact screw of the neighboring inverter module, and the contact screw is then tightened, thereby establishing a shake-proof contact between the intermediate circuit conductor rails of two neighboring inverter modules. Both these conductor rails are covered by a protective cap which is lined with EMC sheet. The EMC sheet is electrically connected by a line to a PE terminal of a module. Each protective cap further includes lateral spring contacts to electrically interconnect the EMC (electromagnetic compatibility) sheets of the individual modules of the modular drive system. As a result, a PE return line of the modular drive system is looped through all modules. The modules of the modular drive system are connected on the front side by a bus. Each module is provided in an area above the intermediate circuit conductor rails with a bay for closed-loop plug-in unit which is provided on the front side with a multipolar socket for connection of a bus, and further multipolar sockets, of which one includes, i.a., terminals for further conduction of a supply voltage.
A drawback of above modular drive systems resides in the space demand for both intermediate circuit conductor rails. The distance of both these intermediate circuit conductor rails is so dimensioned that the connection bracket of one conductor rail is prevented from touching the other conductor rail, when installing or dismantling an inverter module in or from the modular drive system. This is done at the expense of space in order to prevent an inadvertent shorting of the d.c. voltage intermediate circuit of the modular drive system. Moreover, handling of the terminal of the PE return line is time-consuming and prone to fail. The need for a pre-designed cable strand or several cables is also required for applying the supply voltage across all modules of the modular drive system.
It would therefore be desirable and advantageous to provide an improved module of a modular drive system to obviate prior art shortcomings.